Add an install type homebrew for OS X runners

[jaxxstorm]

Signed-off-by: Lee Briggs lee@leebriggs.co.uk

[Copilot]

Pull request overview

Adds a Homebrew-based install path for macOS runners, with CI coverage to exercise both the Homebrew and “build from source” fallback flows.

Changes:

• Add macOS install logic that prefers Homebrew when available and matches the requested version; otherwise fall back to building from source.
• Start tailscaled via brew services when installed with Homebrew and skip caching for Homebrew-managed installs.
• Add smoke/unit-style tests and update workflows to exercise both macOS install types and run local smoke tests in CI.

Reviewed changes

Copilot reviewed 5 out of 7 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/main.ts	Implements Homebrew availability/version checks, Homebrew install path, and Homebrew service start logic; adjusts install return type for downstream decisions (cache/start).
test/macos-homebrew.test.js	Adds source/bundle string-match tests to assert the Homebrew logic is present in src/main.ts and the bundled action.
package.json	Adds test and test:smoke scripts (build + Node test runner).
.github/workflows/test.yml	Extends matrix with an explicit install-type and adds steps to resolve the Homebrew formula version / force the source path; verifies the chosen path.
.github/workflows/smoke-test.yml	Runs npm test (build + local smoke tests) instead of only building.
dist/logout/index.js	Re-bundled output update (generated artifact).

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